Prior art recreational towcraft are designed to carry one or more riders in a prone, seated, or kneeling position, and are intended to be towed at a safe distance behind the powered towing craft. Enjoyment of this activity is derived by virtue of the close proximity of the rider to the water which lends a sensation of high speed. Other aspects of this activity which have broad appeal to a large populace are that the rider or riders do not need to possess certain skills, strength, coordination, or balance in order to enjoy this water sport. Consequently, it is an activity in which the whole family can participate.
Prior art towcraft, steerable and non-steerable alike, have a number of drawbacks. The primary drawback of these recreational devices is the inability to satisfactorily maneuver the device from side to side; that is, to be able to easily and controllably cross and sometimes jump the power boat's wake while the boat is traveling in a straight line. To be simply towed in the prop wash directly behind the power boat or other powered towing craft is not as much fun as quickly “attacking” the wake, loitering along one side, balancing on its ridge, or, crossing over to the calm water outside of the wake. In order for prior art non-steerable towcraft to cross the boat's wake, the boat driver, in coordination with the boat's observer, must cause the boat to make large S-turns while traversing a lake or river. These large S-turns tend to occupy a large amount of space on the lake and can significantly increase the risk of serious injury to the rider or riders of non-steerable towcraft and prior art steerable towcraft.
Many tubing accidents occur because the boat driver either turns too sharply and whips the towcraft too hard or too far to one side of the boat or causes the towcraft to be slung into the path of an oncoming skier, boat, or, to strike a stationary object such as a dock or buoy.
Another deficiency associated with prior art towcraft which claim to be steerable relates to those times when a power boat driver must make a turn; for example, to follow the course of a river, to turn around at the end of a lake or other body of water, to avoid other water traffic, or to return to a launching point. In these instances the towcraft rider should be able to maintain any desired position behind the power boat (preferably, to the inside of the turn).
A further drawback of prior art claimed steerable towcraft relates to directional control of the craft. While certain designs claim to be able to maintain a certain angle relative to a boat's direction of travel, when the boat is traveling in a straight line, the manner in which they dispatch this steering action does not inspire much confidence on the part of the rider. Prior art towcraft generally suffer from poor directional stability; for example, this can take the form of poor or delayed directional responsiveness to steering inputs, induced oscillations, or inadvertent direction changes.
In order to differentiate between the several types of steering approaches adopted by the prior art, a system of classes has been devised. What sets each class apart is a distinguishing characteristic; such as, a principal feature or a claimed action (by the towcraft or its rider). The first class (Class 1) principally involves rider leaning or weight-shifting. The second class (Class 2) is where the entire body of the towcraft is rotated about its center. The third class (Class 3) involves simple manipulation of one or more rudders and a fixed forward towline attachment point. The fourth class (Class 4) involves a combination of craft rotation and one or more rudders at the rear of the towcraft.
Steerable towcraft which relies on leaning (Class 1) typically have aft-mounted, or mid-mounted, off-angle (relative to the craft's longitudinal axis), spaced-apart fins or sponsons which project downward or at an angle and are sewn or bonded to the lower sides or bottom of the fabric bag or cover assembly, or, are simply bonded to the inflated chamber itself, if there is no cover. During straight and level operations, the fins are intended to be out of the water, or partially out of the water. One example of a Class I towcraft is disclosed by U.S. Pat. No. 5,702,278 which describes that, by leaning to one side, the towcraft may be made to turn in that direction.
U.S. Pat. No. 5,702,278 depicts a sponson shaped according to a wedge. Severely tapered sponsons, whose thickness markedly decreases from the base to the distal edge, are disadvantageous due to the higher drag associated with that shape, and, when at nominal towing speed, can itself be made to plane, which, decreases the engagement of the sponson with the water.
U.S. Pat. No. 6,247,984 also discloses towcraft with a fixed forward towline attachment point and alternately engageable fins or sponsons.
Class 2 steerable towcraft are ones which turn the entire body or hull of the towcraft about a central vertical axis as in the manner of a wakeboard. There are a number of approaches the prior art has taken with regard to the construction of Class 2 steerable towcraft. Deficiencies associated with one type are a slow and imprecise steering response rate, and, an inability for the rider to stay with the craft during aggressive steering maneuvers. Another type is costly to manufacture and does not provide an exciting ride experience. The latter style is made in the shape of a boat (U.S. Pat. No. 5,881,665). Other examples of Class 2 towcraft are disclosed in U.S. Pat. No. 5,888,110, and U.S. Pat. No. 5,899,782. These patents disclose inflatable devices which are made to be rotated horizontally in the water while being towed behind a power boat or other powered craft.
A Class 3 style of towcraft is disclosed in U.S. Pat. No. 5,906,526 which has its towline attachment method is a simple fixture at the front of the craft. A variation of a Class 3 style of towcraft having rudders and a fixed forward towline attachment point is described in U.S. Pat. No. 5,247,898.
An example of a Class 4 claimed steerable towcraft is disclosed in U.S. Pat. No. 6,182,594. It utilizes a semi-rigid shell, curved track and trolley, inflated inner tube, and separate rope mounted steering grips which are connected by means of ropes to a rudder located at the rear of the towcraft.
U.S. Pat. No. 5,076,189 discloses a towable water sled which features a forward pivoting handlebar, a pair of pivoting, transversely spaced-apart rudders near the stern, and a fixed towline attachment means.
U.S. Pat. No. 6,477,976 discloses a costly towcraft constructed in the shape of a tunnel-hulled personal watercraft (PWC) with spaced-apart sponsons which comprise the forward half of the towcraft's overall length.
U.S. Pat. No. 6,638,125 describes a towboard which consists of a long narrow board-shaped form with a hinged extension rising up and back from the front of the craft.
It is important that the towcraft not be overly sensitive to the variations in water and operational conditions typically encountered during water sport towing exercises.
Therefore, one object of the present invention is to provide a low-cost towcraft which is highly maneuverable and easily controllable by an intuitive leaning action and/or has a transverse differential drag condition, or a combination of the two features.
A further object of the present invention is to provide a pivoting forward rudder style of towcraft which may be made convertible to a steer-by-leaning type.
Another object of the present invention is to provide a compact, economically manufactured, towcraft capable of being controllably steered with little effort at all reasonable towing speeds.
It is another object of the present invention to provide a towcraft that features neutral handling characteristics where the steering input is intuitive, the steering response is proportional to the input, and preferably, large steering input displacements are not required.
It is another object of the present invention that the steerable towcraft accommodates and provides a stable, predictable, responsive, towing experience for riders, regardless of their height, weight or skill level.
It is a further object that the steerable towcraft is able to be operated by at least one rider such that the rider is able to maneuver and stay to the inside of a turn regardless of the maneuvering of the power boat towing the craft.
It is another object of the present invention is to provide a steerable towcraft having a steering action that preferably aims the front of the towcraft in the direction of travel.
It is still a further object of the present invention that the rider or riders be provided with means of being able to stay with the towcraft during aggressive maneuvers and during rough water conditions.
A still further object of the present invention is to be able to adjust the towcraft's maneuverability and handling characteristics in the water according to the rider's preferences.
A still further object of the present invention is to provide a towcraft which is easily transportable in the back of a vehicle (SUV, pick-up truck, station wagon, etc.) or on top of a vehicle, without requiring the use of a trailer. The towcraft should be able to be quickly and easily disassembled with a minimum or complete absence of tools.
A still further object of the present invention is to provide a towcraft which easily lifted and carried by one or two people.
A still further object of the present invention is to provide a steerable towcraft is provided which is comfortable to sit in or to lie prone on, especially when landing back on the craft after performing a wake jump.
A still further object of the present invention is to provide a highly stable platform which is not easily upset when at rest in the water.
And finally, it is an object of the present invention to provide a towcraft that is able to be easily emptied of any accumulated water by one person while that person is in the water.